It is often desirable for electronic devices to transmit data, transfer power, or otherwise communicate one with another. Reliable communication is especially important in medical devices, where miscommunication may result in device malfunction and harm to a patient. For example, many implantable medical devices, such as implantable stimulators, are configured to transmit status updates to and receive operational instructions and power from one or more external devices. Without accurate communication, these implantable medical devices could cease to function properly.
An exemplary implantable medical device is an implantable cochlear stimulator (ICS), which may be used to treat sensorineural hearing loss. An ICS seeks to bypass the hair cells in the cochlea, which are essential to hearing but which may not be functioning properly, by presenting electrical stimulation directly to the auditory nerve fibers. The stimulation leads to the perception of sound in the brain and at least partial restoration of hearing function.
Many implantable medical devices are intended to remain permanently in the body of a patient once they are implanted. For this reason, one or more external devices may be configured to communicate with and support an implantable medical device by transmitting various control signals (e.g., stimulation parameters) to the implantable medical device and/or provide power to the implantable medical device. For example, a behind-the-ear (BTE) signal processor may be positioned behind the ear and used to support the ICS by transmitting various stimulation parameters to the ICS and/or providing power to the ICS.
An external device may also be configured to periodically receive status signals from an implantable medical device to ensure that the implantable medical device is functioning properly. To this end, implantable medical devices often include a back-telemetry transmitter configured to transmit one or more status signals to an external device via, e.g., a wireless telemetry link.
However, back-telemetry transmitters often consume a relatively large amount of power. Hence, the current drain on the implantable medical device caused by enabling the back-telemetry transmitter can significantly lower the power supply voltage(s) in the implantable medical device.
In cases where the implantable medical device includes an ICS, the current drain caused by back-telemetry transmitters is often perceptible to the user due to reduced stimulation compliance voltages. To alleviate the reduced compliance voltage levels, the back-telemetry transmitter may be enabled or left “on” at all times. However, this requires additional power to be supplied to the ICS continuously, which may lead to reduced battery life in the BTE signal processor.
Alternatively, the BTE signal processor may temporarily increase the power supplied to the ICS prior to turning on the back-telemetry transmitter in order to alleviate the reduced stimulation compliance voltages. However, such an approach adds undesirable cost and complexity to the system power management hardware and software, induces perceptible noise into the processor audio circuits due to rapidly switching loads on the processor's power supply, and, in some cases, can still cause perceptible fluctuations in the compliance voltage.